The Globe Flashcards
Why does earth rotate on its own axis(6)
Earth spins BC of the way it was formed
Solar system formed from a huge cloud of gas and dust
It started to collapse under its own gravity
As the cloud collapsed it started to spin
As the planets were formed they kept the spinning motion
Speed 1675km/h
Origin of day and night (6)
The earth rotates from east to west around its own axis
One rotation=24h
One side of the earth is facing the sun
One side is facing away from the sun
The boarder between day and night is so called circle of illumination
At any given time one half will experience day and the other half night
Rotation and time
Time at any place is determined at the meridian on which that place is located
In 1h the earth rotates through =360 degrees ÷24h=15 degrees
15 degrees =1 hour(60 min)
1 degree =60 min÷15
1 degree = 4 min
This means that if a place is 1 degree from another than their time will differ 4 minutes
How do you tell if the time of a place is ahead or behind
East= ahead
West =behind
How to calculate the time of places (6)
Determine the difference in degrees between the two places
Multiply the number of degrees by 4 minutes
That dives to the difference in minutes
Divide the answer by 60 for hours
Add the time difference if the place is east of the other
Minus the time difference if the place is west of the other
What is a time zone
A time zone is a geographical region where the standard time is used
Why do we have time zones (4)
During the 19the century towns had their own time according to its longitude
It caused many problems modern development improved more
The Greenwich meridian wat adopted in 1884 as the initial or prime meridian for longitude and time keeping
Now towns and regions in a country all had the same time
How do time zones work (5)
Each time zone is approximately 15 degrees wide
Which means an hour difference between 2 time zones
There are 24 time zones
The shape of a time zone is changed, in practice, to match internal and international boarders
One would need to divide the longitude, in degrees, by 15 to find the appropriate time zone in hours
Example:
At 150 degrees west longitude, the time would be 150÷15=10 hours behind GMT (Greenwich mean time)
At 75 degrees east the time would be 75÷15=5 hours behind GMT
